Preventing brain injury in newborns with congenital heart disease: brain imaging and innovative trial designs

Prevalence and Risk Factors for Cerebral Palsy in Children With Congenital Heart Disease Based on Risk of Surgical Mortality

BACKGROUND

Children with congenital heart disease (CHD) have a higher prevalence of motor impairment secondary to brain injury, resulting in cerebral palsy (CP). The purpose of this study is to determine the prevalence of CP in CHD in a single-center cohort, stratify risk based on surgical mortality using Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) categories and identify risk factors.

METHODS

Retrospective cohort study of pediatric patients registered in the University of Florida (UF) Society of Thoracic Surgeons Congenital Heart Surgery database from 2006 to 2017 with a diagnosis of CHD who continued follow-up for more than two years at UF.

RESULTS

A total of 701 children with CHD met inclusion criteria. Children identified to have CP were 54 (7.7%). Most common presentation was spastic hemiplegic CP with a Gross Motor Function Classification System of level 2. Analysis of surgical and intensive care factors between the two groups showed that children with CHD and CP had longer time from admission to surgery (P = 0.003), higher STAT categories 4 and 5 (P = 0.038), and higher frequency of brain injury and seizures (P < 0.001). Developmental disabilities and rehabilitation needs were significantly greater for children with CHD and CP when compared with those with CHD alone (P < 0.001).

CONCLUSIONS

In our cohort, 7.7% children with CHD develop CP; this is significantly higher than the 2010 US population estimate of 0.3%. Our study suggests higher STAT categories, brain injury, and seizures are associated with developing CP in children with CHD.

Early brain magnetic resonance imaging findings and neurodevelopmental outcome in children with congenital heart disease: A systematic review

AIM

To investigate the association between early brain magnetic resonance imaging (MRI) findings and neurodevelopmental outcome (NDO) in children with congenital heart disease (CHD).

METHOD

A search for studies was conducted in Embase, Medline, Web of Science, Cochrane Central, PsycINFO, and Google Scholar. Observational and interventional studies were included, in which patients with CHD underwent surgery before 2 months of age, a brain MRI scan in the first year of life, and neurodevelopmental assessment beyond the age of 1 year.

RESULTS

Eighteen studies were included. Thirteen found an association between either quantitative or qualitative brain metrics and NDO: 5 out of 7 studies showed decreased brain volume was significantly associated with worse NDO, as did 7 out of 10 studies on brain injury. Scanning protocols and neurodevelopmental tests varied strongly.

INTERPRETATION

Reduced brain volume and brain injury in patients with CHD can be associated with impaired NDO, yet standardized scanning protocols and neurodevelopmental assessment are needed to further unravel trajectories of impaired brain development and its effects on outcome.

Screening and Evaluation of Neurodevelopmental Impairments in Infants Under 6 Months of Age with Congenital Heart Disease

Clinical evaluation of neurodevelopmental impairments before 6 months of age is needed in congenital heart disease (CHD) to promote early referral to developmental interventions. The objective was to identify the risk of cerebral palsy (CP) and to compare neurodevelopment outcomes in infants with and without CHD. In a longitudinal study, 30 infants with CHD and 15 infants without CHD were assessed at 1 month, 3 months, and 6 months of age. Included measures were General Movement Assessment (GMA), Test of Infant Motor Performance (TIMP) and the Bayley Scale of Infant Development, third edition (Bayley-III), selected to identify the risk of CP, document neurodevelopmental impairments and infants' eligibility for early intervention services. Abnormal GMA categories were found in the CHD group where 48% had poor repertoire and 15% were at high risk of CP. At 3 months of age, CHD group had significantly lower TIMP scores compared to infants without CHD [t(41) = 6.57, p = 0.01]. All infants in the study had higher Bayley-III scores at 6 months than at 3 months of age. Infants with CHD had lower gross motor, fine motor and cognitive Bayley-III scores compared to their peers without CHD. Over time infants without CHD outperformed the CHD group in the gross motor skills [F_(1,41) = 11.76, p = .001]. Higher prevalence of abnormal GMs, lower TIMP and Bayley-III were found in infants with single ventricle physiology compared to two-ventricle physiology. The risk of CP exists in infants with CHD, and these infants have worse outcomes compared to their peers without CHD. These differences are intensified in the single ventricle population.Clinical Trial Registration National Institute of Health, Unique identifier: NCT03104751; Date of registration-April 7, 2017.

Motor Impairment in Children With Congenital Heart Defects: A Systematic Review

CONTEXT

With improvements in survival rates in newborns with congenital heart defects (CHDs), focus has now shifted toward enhancing neurodevelopmental outcomes across their life span.

OBJECTIVE

To systematically review the prevalence and extent of motor difficulties in infants, children, and adolescents with CHD requiring open-heart surgery.

DATA SOURCES

Data sources included Embase, Medline and the Cumulative Index to Nursing and Allied Health Literature.

STUDY SELECTION

Original studies published between 1997 and 2019 examining gross and/or fine motor skills in children born with a CHD requiring open-heart surgery were selected.

DATA EXTRACTION

The prevalence of motor impairments and mean scores on standardized motor assessments were extracted. Findings were grouped in 5 categories on the basis of the age of the children.

RESULTS

Forty-six original studies were included in this systematic review. The prevalence of mild to severe motor impairments (scores <-1 SD below normative data or controls) across childhood ranged from 12.3% to 68.6%, and prevalence ranged from 0% to 60.0% for severe motor impairments (<-2 SDs). Although our results suggest that the overall prevalence of motor impairments <-1 SD remains rather constant across childhood and adolescence, severe motor impairments (<-2 SDs) appear to be more prevalent in younger children.

LIMITATIONS

Variability in sampling and methodology between the reviewed studies is the most important limitation of this review.

CONCLUSIONS

The results of this review highlight that infants with CHD have an increased risk of motor impairments across infancy, childhood, and adolescence. These findings stress the importance of systematic screening or evaluation of motor skills across childhood and adolescence in children with CHD.

Neonatal Brain Injury and Timing of Neurodevelopmental Assessment in Patients With Congenital Heart Disease

BACKGROUND

Brain injury (BI) is reported in 60% of newborns with critical congenital heart disease as white matter injury (WMI) or stroke. Neurodevelopmental (ND) impairments are reported in these patients. The relationship between neonatal BI and ND outcome has not been established.

OBJECTIVES

This study sought to determine the association between peri-operative BI and ND outcomes in infants with single ventricle physiology (SVP) and d-transposition of the great arteries (d-TGA).

METHODS

Term newborns with d-TGA and SVP had pre-operative and post-operative brain magnetic resonance imaging and ND outcomes assessed at 12 and 30 months with the Bayley Scales of Infant Development-II. BI was categorized by the brain injury severity score and WMI was quantified by volumetric analysis.

RESULTS

A total of 104 infants had follow-up at 12 months and 70 had follow-up at 30 months. At 12 months, only clinical variables were associated with ND outcome. At 30 months, subjects with moderate-to-severe WMI had significantly lower Psychomotor Development Index (PDI) scores (13 points lower) as compared with those with none or minimal WMI for d-TGA and SVP (p = 0.03 and p = 0.05, respectively) after adjusting for various factors. Quantitative WMI volume was likewise associated. Stroke was not associated with outcome. The Bland-Altman limits of agreement for PDI scores at 12 and 30 months were wide (-40.3 to 31.2) across the range of mean PDI values.

CONCLUSIONS

Increasing burden of WMI is associated with worse motor outcomes at 30 months for infants with critical congenital heart disease, whereas no adverse association was seen between small strokes and outcome. These results support the utility of neonatal brain magnetic resonance imaging in this population to aid in predicting later outcomes and the importance of ND follow-up beyond 1 year of age.

Brain injury with systemic inflammation in newborns with congenital heart disease undergoing heart surgery

The potential role of systemic inflammation on brain injury in newborns with congenital heart disease (CHD) was assessed by measuring levels of central nervous system (CNS)-derived proteins in serum prior to and following cardiac surgery. A total of 23 newborns (gestational age, 39±1 weeks) with a diagnosis of CHD that required cardiac surgery with cardiopulmonary bypass (CPB) were enrolled in the current study. Serum samples were collected immediately prior to surgery and 2, 24 and 48 h following CPB, and serum levels of phosphorylated neurofilament-heavy subunit (pNF-H), neuron-specific enolase (NSE) and S100B were analyzed. Systemic inflammation was assessed by measuring serum concentrations of complement C5a and complement sC5b9, and the following cytokines: Interleukin (IL)-1β, IL-6, IL-8, IL-10, IL12p70, interferon γ and tumor necrosis factor (TNF)-α. Analysis of cord blood from normal term deliveries (n=26) provided surrogate normative values for newborns. pNF-H and S100B were 2.4- to 2.8-fold higher (P<0.0001) in patient sera than in cord blood prior to surgery and remained elevated following CPB. Pre-surgical serum pNF-H and S100B levels directly correlated with interleukin (IL)-12p70 (ρ=0.442, P<0.05). pNF-H was inversely correlated with arterial pO₂ prior to surgery (ρ=−0.493, P=0.01) and directly correlated with arterial pCO₂ post-CPB (ρ=0.426, P<0.05), suggesting that tissue hypoxia and inflammation contribute to blood brain barrier (BBB) dysfunction and neuronal injury. Serum IL12p70, IL-6, IL-8, IL-10 and TNF-α levels were significantly higher in patients than in normal cord blood and levels of these cytokines increased following CPB (P<0.001). Activation of complement was observed in all patients prior to surgery, and serum C5a and sC5b9 remained elevated up to 48 h post-surgery. Furthermore, they were correlated (P<0.05) with low arterial pO₂, high pCO₂ and elevated arterial pressure in the postoperative period. Length of mechanical ventilation was associated directly with post-surgery serum IL-12p70 and IL-8 concentrations (P<0.05). Elevated serum concentrations of pNF-H and S100B in neonates with CHD suggest BBB dysfunction and CNS injury, with concurrent hypoxemia and an activated inflammatory response potentiating this effect.

Arterial ischemic stroke in children with cardiac disease

OBJECTIVE

To describe the spectrum of cardiac disorders, timing in relation to interventional procedures, and outcome in children with cardiac disease and arterial ischemic stroke (AIS).

METHODS

Children younger than 18 years with cardiac disease and radiologically confirmed AIS admitted to the Royal Children's Hospital Melbourne between 1993 and 2010 were retrospectively identified using ICD-9 and ICD-10 searches.

RESULTS

Seventy-six children with cardiac disease and radiologically confirmed AIS were identified with the median age at diagnosis of 5 months (interquartile range 0-58). Cardiac lesions included cyanotic congenital heart disease (CHD) in 42 (55%), acyanotic heart disease in 24 (29%), cardiomyopathies/myocarditis in 6 (8%), infective endocarditis in 3 (4%), and primary arrhythmias in 3 (4%). Stroke occurred following cardiac procedures in 52 patients (68%): 41 post cardiac surgery (4.6 strokes per 1,000 surgical procedures) and 11 post cardiac catheterization (1.7 strokes per 1,000 catheterizations). The median time from procedure to diagnosis of stroke was 3 days (interquartile range 2-7), with 68% (95% confidence interval 58%-79%) of strokes estimated to occur within the periprocedural period. Prevalence of periprocedural stroke varied by diagnostic category, but was most common in patients with cyanotic CHD undergoing palliative surgery (22/2,256, 1%) (p < 0.005). There were 3 AIS-related deaths, and 54 survivors (84%) had persisting neurologic deficits.

CONCLUSIONS

Infants with cyanotic CHD were most frequently affected by AIS during the periprocedural period. Prospective cohort studies are required to determine effective primary and secondary prevention strategies.

Neuroprotective strategies--what do we really need to know?

While preliminary data are encouraging, definitive data are lacking to conclusively demonstrate the benefit of perioperative neurologic monitoring in improving neurodevelopmental outcomes in children who require surgery for congenital heart disease. Nonetheless, in the current era, some form of perioperative neurologic monitoring is important. Strategies include bicortical near infrared spectroscopy monitoring in the pre- and postoperative periods along with bicortical near infrared spectroscopy and transcranial Doppler intraoperatively. These monitors provide real-time information concerning cerebral oxygen delivery and blood flow. These strategies will allow us to refine treatments to optimize neurodevelopmental potential in children with congenital heart disease.

Multi-tiered analysis of brain injury in neonates with congenital heart disease

Early brain injury occurs in newborns with congenital heart disease (CHD) placing them at risk for impaired neurodevelopmental outcomes. Predictors for preoperative brain injury have not been well described in CHD newborns. This study aimed to analyze, retrospectively, brain magnetic resonance imaging (MRI) in a heterogeneous group of newborns who had CHD surgery during the first month of life using a detailed qualitative CHD MRI Injury Score, quantitative imaging assessments (regional apparent diffusion coefficient [ADC] values and brain volumes), and clinical characteristics. Seventy-three newborns who had CHD surgery at 8 ± 5 (mean ± SD) days of life and preoperative brain MRI were included; 38 also had postoperative MRI. Thirty-four (34 of 73, 47 %) had at least one type of preoperative brain injury, and 28 of 38 (74 %) had postoperative brain injury. The 5-min APGAR score was negatively associated with preoperative injury, but there was no difference between CHD types. Infants with intraparenchymal hemorrhage, deep gray matter injury, and/or watershed infarcts had the highest CHD MRI Injury Scores. ADC values and brain volumes were not different in infants with different CHD types or in those with and without brain injury. In a mixed group of CHD newborns, brain injury was found preoperatively on MRI in almost 50 %, and there were no significant baseline characteristic differences to predict this early brain injury except 5-min APGAR score. We conclude that all infants, regardless of CHD type, who require early surgery should be evaluated with MRI because they are all at high risk for brain injury.

Prematurity and congenital heart disease

Significant advances in technology and therapy have led to dramatic improvements in the survival of preterm babies over the last 2 decades. Similarly, improvements in surgical and cardiac intensive care techniques have increased the feasibility of supporting even very small babies to the point of surgical repair, leading some to adopt an approach of early and complete surgical repair in preterm infants, with the aim of minimizing potential preoperative morbidity associated with extended medical management or surgical palliation. (1,2) However, multiple diagnostic and therapeutic challenges complicate the care of premature infants. Major errors in echocardiography are more common in neonates weighing less than 2.5 kg, (3) and the ideal timing and type of surgical intervention in premature infants remains unknown. These problems are compounded by the need for critical care practices that optimize management of immature cardiopulmonary, gastrointestinal, and neurological systems. This review will summarize some of the recent advances in neonatal and perinatal medicine, which have the potential to contribute to improved management of preterm infants with critical cardiac disease.

Biomarkers of brain damage in preterm infants

OBJECTIVE

There is growing evidence on the usefulness of biomarkers in the early detection of preterm infants at risk for brain damage. However, among different tools Activin A, S100B protein and adrenomedullin assessment offer the possibility to investigate brain/multiorgan function and development. This could be especially useful in perinatal medicine that requires even more non-invasive techniques in order to fulfill the minimal handling in diagnostic and therapeutic strategy performance.

MATERIALS AND METHODS

The concept of Unconventional Biological Fluid (UBF: urine and saliva) is becoming even stronger and regards the assessment in non-invasive biological fluids of biochemical markers involved in the cascade of events leading to brain damage.

RESULTS

Activin A, S100B protein and adrenomedullin in UBF were increased in preterm newborns developing brain damage and/or ominous outcome.

CONCLUSIONS

The present manuscript offers an update on the usefulness of Activin A, S100B protein an adrenomedullin in UBF as brain damage markers. The findings open a new cue on the use of these markers in daily neonatal intensive care unit (NICU) activities.

Impact of congenital heart disease on brain development in newborn infants

Objective:

To assess brain development and brain injury in neonates with cyanotic and acyanotic congenital heart disease (CHD).

Methods:

The study included 52 term infants with CHD who were divided into two groups: Cyanotic (n=21) and acyanotic (n=31). Fifteen healthy neonates of matched age and sex were enrolled in the study as controls. Three-dimensional proton magnetic resonance spectroscopic imaging and diffusion tensor imaging were used to assess brain development and injury. We calculated the ratio of N-acetylaspartate (NAA) to choline (which increases with maturation), average diffusivity (which decreases with maturation), fractional anisotropy of white matter (which increases with maturation), and the ratio of lactate to choline (which increases with brain injury).

Results:

As compared with control neonates, those with CHD had significant decrease in NAA/choline ratio (P<0.001), significant increase in lactate/choline ratio (P<0.0001), significant increase in average diffusivity (P<0.0001), and significant decrease of white matter fractional anisotropy (P<0.001). Neonates with cyanotic CHD had significant less brain development and more brain injury than those with acyanotic CHD (P<0.05).

Conclusions:

Newborn infants with cyanotic and acyanotic CHD are at high risk of brain injury and impaired brain maturity.

Early developmental outcomes following major noncardiac and cardiac surgery in term infants: a population-based study

OBJECTIVE

To ascertain developmental differences between term infants after major noncardiac surgery and cardiac surgery compared with healthy control infants in New South Wales, Australia.

STUDY DESIGN

This prospective population-based cohort study enrolled infants between August 1, 2006, and December 31, 2008, who required major noncardiac surgery within the first 90 days of life. Developmental outcomes were compared in these children, cohorts of term infants requiring cardiac surgery, and healthy controls. Infants were assessed at 1 year of age using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III).

RESULTS

Of the 784 infants enrolled, 688 (90.2%) of infants alive at 1 year were assessed. Of these, 539 infants were term and were included in the present analysis. Compared with controls, the infants who underwent cardiac surgery had significantly lower (P < .001) mean scores in all 5 BSID-III subscales, and the infants who underwent noncardiac surgery had significantly lower (P < .05) mean scores in 4 of the 5 BSID-III subscales. The greatest difference was in the incidence of gross motor delay in both the cardiac surgery group (OR, 0.25; 95% CI, 0.16-0.41) and the noncardiac surgery group (OR, 0.41; 95% CI, 0.26-0.63).

CONCLUSION

This unique population-based prospective study compared the developmental outcomes of infants who underwent major noncardiac surgery and cardiac surgery. Major surgery in infants was found to be significantly associated with developmental delay at 1 year of age compared with control infants. These data have important implications for interventions and clinical review in the first year of life.

Regional differences in susceptibility to hypoxic-ischemic injury in the preterm brain: exploring the spectrum from white matter loss to selective grey matter injury in a rat model

Models of premature brain injury have largely focused on the white matter injury thought to underlie periventricular leukomalacia (PVL). However, with increased survival of very low birth weight infants, injury patterns involving grey matter are now recognized. We aimed to determine how grey matter lesions relate to hypoxic-ischemic- (HI) mediated white matter injury by modifying our rat model of PVL. Following HI, microglial infiltration, astrocytosis, and neuronal and axonal degeneration increased in a region-specific manner dependent on the severity of myelin loss in pericallosal white matter. The spectrum of injury ranged from mild, where diffuse white matter abnormalities were dominant and were associated with mild axonal injury and local microglial activation, to severe HI injury characterized by focal MBP loss, widespread neuronal degeneration, axonal damage, and gliosis throughout the neocortex, caudate putamen, and thalamus. In sum, selective regional white matter loss occurs in the preterm rat concomitantly with a clinically relevant spectrum of grey matter injury. These data demonstrate an interspecies similarity of brain injury patterns and further substantiates the reliable use of this model for the study of preterm brain injury.

Treatment advances in neonatal neuroprotection and neurointensive care

Knowledge of the nature, prognosis, and ways to treat brain lesions in neonatal infants has increased remarkably. Neonatal hypoxic-ischaemic encephalopathy (HIE) in term infants, mirrors a progressive cascade of excito-oxidative events that unfold in the brain after an asphyxial insult. In the laboratory, this cascade can be blocked to protect brain tissue through the process of neuroprotection. However, proof of a clinical effect was lacking until the publication of three positive randomised controlled trials of moderate hypothermia for term infants with HIE. These results have greatly improved treatment prospects for babies with asphyxia and altered understanding of the theory of neuroprotection. The studies show that moderate hypothermia within 6 h of asphyxia improves survival without cerebral palsy or other disability by about 40% and reduces death or neurological disability by nearly 30%. The search is on to discover adjuvant treatments that can further enhance the effects of hypothermia.

Development of axonal pathways in the human fetal fronto-limbic brain: histochemical characterization and diffusion tensor imaging

The development of cortical axonal pathways in the human brain begins during the transition between the embryonic and fetal period, happens in a series of sequential events, and leads to the establishment of major long trajectories by the neonatal period. We have correlated histochemical markers (acetylcholinesterase (AChE) histochemistry, antibody against synaptic protein SNAP-25 (SNAP-25-immunoreactivity) and neurofilament 200) with the diffusion tensor imaging (DTI) database in order to make a reconstruction of the origin, growth pattern and termination of the pathways in the period between 8 and 34 postconceptual weeks (PCW). Histological sections revealed that the initial outgrowth and formation of joined trajectories of subcortico-frontal pathways (external capsule, cerebral stalk-internal capsule) and limbic bundles (fornix, stria terminalis, amygdaloid radiation) occur by 10 PCW. As early as 11 PCW, major afferent fibers invade the corticostriatal junction. At 13-14 PCW, axonal pathways from the thalamus and basal forebrain approach the deep moiety of the cortical plate, causing the first lamination. The period between 15 and 18 PCW is dominated by elaboration of the periventricular crossroads, sagittal strata and spread of fibers in the subplate and marginal zone. Tracing of fibers in the subplate with DTI is unsuccessful due to the isotropy of this zone. Penetration of the cortical plate occurs after 24-26 PCW. In conclusion, frontal axonal pathways form the periventricular crossroads, sagittal strata and 'waiting' compartments during the path-finding and penetration of the cortical plate. Histochemistry is advantageous in the demonstration of a growth pattern, whereas DTI is unique for demonstrating axonal trajectories. The complexity of fibers is the biological substrate of selective vulnerability of the fetal white matter.

Towards improved animal models of neonatal white matter injury associated with cerebral palsy

Newborn neurological injuries are the leading cause of intellectual and motor disabilities that are associated with cerebral palsy. Cerebral white matter injury is a common feature in hypoxic-ischemic encephalopathy (HIE), which affects full-term infants, and in periventricular leukomalacia (PVL), which affects preterm infants. This article discusses recent efforts to model neonatal white matter injury using mammalian systems. We emphasize that a comprehensive understanding of oligodendrocyte development and physiology is crucial for obtaining new insights into the pathobiology of HIE and PVL as well as for the generation of more sophisticated and faithful animal models.

Brain maturity and brain injury in newborns with cyanotic congenital heart disease

Patients with congenital heart disease (CHD) are at high risk for adverse neurodevelopmental outcomes. The aim of this work was to assess brain maturity and brain injury in newborns with cyanotic CHD using proton magnetic resonance spectroscopy (MRS). The study included 38 newborns with cyanotic CHD (study group) and 20 healthy full-term newborns (control group) matched together regarding gestational age and sex. Three-dimensional MRS showed that the mean ratio of N-acetylaspartate to choline (Ch) was significantly lower in newborns with cyanotic CHD (0.55 ± 0.08) compared with controls (0.67 ± 0.11) (p < 0.001). However, the mean ratio of lactate to Ch metabolite was significantly higher in the studied cases (0.14 ± 0.04) compared with controls (0.09 ± 0.04) (p < 0.001). The mean value for average diffusivity was 1.41 ± 0.06 in newborns with cyanotic CHD compared with 1.27 ± 0.07 in control newborns (p < 0.001), and the mean value for white-matter fractional anisotropy was 0.19 ± 0.03 in cyanotic newborns and 0.25 ± 0.08 in controls (p < 0.001). Newborns with cyanotic CHD are at increased risk of cerebral white matter injury as well as poor brain maturity. MRS provides a surrogate marker for early detection of such brain abnormalities.

New approaches to neuroprotection in infant heart surgery

Advances in surgical techniques and perioperative management have led to dramatic improvements in outcomes for children with complex congenital heart disease (CHD). As the number of survivors continues to grow, clinicians are becoming increasingly aware that adverse neurodevelopmental outcomes after surgical repair of CHD represent a significant cause of morbidity, with widespread neuropsychologic deficits in as many as 50% of these children by the time they reach school age. Modifications of intraoperative management have yet to measurably impact long-term neurologic outcomes. However, exciting advances in our understanding of the underlying mechanisms of cellular injury and of the events that mediate endogenous cellular protection have provided a variety of new potential targets for the assessment, prevention, and treatment of neurologic injury in patients with CHD. In this review, we will discuss the unique challenges to developing neuroprotective strategies in children with CHD and consider how multisystem approaches to neuroprotection, such as ischemic preconditioning, will be the focus of ongoing efforts to develop new diagnostic tools and therapies. Although significant challenges remain, tremendous opportunity exists for the development of diagnostic and therapeutic interventions that can serve to limit neurologic injury and ultimately improve outcomes for infants and children with CHD.

From selective vulnerability to connectivity: insights from newborn brain imaging

The ability to image the newborn brain during development has provided new information regarding the effects of injury on brain development at different vulnerable time periods. Studies in animal models of brain injury correlate beautifully with what is now observed in the human newborn. We now know that injury at term primarily results in grey matter injury while injury in the premature brain predominantly results in a pattern of white matter injury, though recent evidence suggests a blurring of this distinction . These injuries affect how the brain matures subsequently and again, imaging has led to new insights that allow us to match function and structure. This review will focus on these patterns of injury that are so crucially determined by age at insult. In addition, this review will highlight how the brain responds to these insults with changes in connectivity that have profound functional consequences.